Method and apparatus for the distribution of multi-media documents

ABSTRACT

Multi-media documents, in the form of digital signals, are fed into a multiplexer/coder by several sub-channels, which are time multiplexed. A control signal is added and the combined signal is modulated into a transmission signal at the transmitter side. At the receiver side, the transmission signal is processed up to the output of a tuner like a normal signal for television. After the tuner, the signal is demodulated, digitized, demultiplexed, and the control information of the control signal is extracted from the bit stream so that by monitoring said control information signal provided with the transmission, a transmission channel decoder enables a multi-media player to read a distributed document according to the program of the user. Alternately, the signal is directly stored by a multi-media player and the stored signal is demodulated, digitized, demultiplexed and the control information of the control signal is extracted from the bit stream so that by monitoring the control information signal provided with the transmission, a transmission channel decoder controls a reproduction device for reproducing a distributed document according to the programming of the user.

BACKGROUND

The present invention relates to simultaneous transmission of severaldifferent information via a television channel in the manner ofmulti-media-distribution and the recording and reproduction ofmulti-media-documents.

So called multi-media-documents are electronic documents which consistsof:

text

still pictures

graphics

digital sound

digital video

any combination of the above mentioned kinds of data.

It is already known to use picture-in-picture television receivers andvideo text for providing different information. But the number ofdifferent information which may be transmitted by a normal televisionchannel is restricted by bandwidth of television signal.

It is also known a multi-media terminal apparatus which cansimultaneously operate a plurality of peripheral equipments connected toother multi-media terminal apparatuses on a network, see EP-A-0 435 344.The multi-media terminal apparatus is connected to other multi-mediaterminal apparatuses via a transmission line having a plurality ofchannels.

SUMMARY OF THE INVENTION

Transmission of digital television signals via direct broadcast satelitesystem (DBS), based on digital compression techniques, is also underdevelopment. Such a system can transmit digitally compressed video andaudio signals and, optionally, associated control/conditional accessdata by means of satellite transmission. A large number of transmissionchannels with a net data rate between 20 to 30 Mbits/sec are provided.To compress video and audio the MPEG I algorithm (motion picture expertgroup) is used.

Therefore it is the task of this invention to build up a system whichenables the distribution, recording and playback of a multiple of multimedia documents with low costs.

The invention is based on the idea of using a television channel orparts of the bandwidth of it to distribute simultaneously a multiple ofmulti media documents, whereas for recording and playback purposealready known devices with additional functionality are used.

The method is that several multi media documents are read into a digitalstorage device like Compact Disc or in a digital video tape. Thesedigital storage devices serve as a source of digital signals on thesending side. The digital signals are fed in several sub-channels intothe multiplexer.

The number of possible subchannels and therefore the number of multimedia documents simultaneously distributed is limited by:

the number of available transmission channels

the bandwidth of each channel

and the bitrate for each subchannel.

For instance the following distribution schemes on one channel arepossible: (Assumption channel capacity 23.6 Mbit/sec) Example 1: 16subchannels at the single Compact Disc (CD) data rate of around1.4Mbit/s Example 2: 3 tv programs subchannels at 6.8 Mbit/s each plus 2subchannels with each single CD data rate Example 3: 2 tv programsubchannels at 8 Mbit/s each plus 2 subchannels with double CD data rateplus 1 subchannel with single CD data rate.

To transmit several subchannels containing different multi mediadocuments the subchannels are time-multiplexed in the transmissionchannel.

This has the following advantages:

flexible usage of the overall channel capacity is possible

otherwise unused remaining bandwitdh within a channel can be used totransmit multi media documents

In accordance with the present invention, there are provided onbroadcasting studio side several sub-channels with average bit ratesranging from several kilobits/s up to the whole channel capacity, whichare fed into a multiplexer. In the multiplexer the sub-channels aretime-multiplexed and a control information is added. Afterwards the datais preferred undergone a channel coding to assure error-freetransmission. The final step at the sending side is the modulation intoan analogous signal and the emission via the different media, e.g.satellite, cable network or terrestrial distribution.

On the receiving side the signal passes the demodulation, error checkand concealment and the demultiplexer after reception via satelite,cable or terestrial. The demodulator treats only one out of severalchannels simultaneously. The task of the demultiplexer is to separatethe different subchannels in one transmission channel and to extract thecontrol information from the data stream.

As storing devices are two classes possible:

a) A device which records the whole data stream of one channel--this isa digital VCR. The selection between the different subchannels is doneat playback time by using the control information included in the bitstream according to the selection of the user.

b) a device which selects and records only one subchannel out of the nsubchannels in one transmission channel--this is a disk-based device andcalled compact disc multi media player.

By monitoring the control information provided with the transmission thetransmission channel decoder causes the compact disc multi-media playerto record the distributed documents according to the programming of theuser.

The transmission channel decoder can be housed in an external box or canbe an integrated part of the compact disc multi-media player.

The distribution can be done during the night when free televisiontransmission channels are available or at all times by means of separatechannels.

The compact disc multi-media player is a superset of the knownCD-I-Player with additional functions. This additional functions are thepossibility to use CD-read-only and CD-writeable such asMagneto-Optical-Disc. Further additions are a remote channel interfacewhich offers the possibility for remote storage of multi-media documentson the Magneto-Optical-Disc.

Optionally the compact disc multi-media player is equipped with a smartcard reader for access permission or prohibition to the data in thedifferent sub-channels.

A further option is the computer interface for the connection to acomputer system.

There are two groups of application in which a compact disc multi-mediaplayer can be used.

The first group of applications relates to a first sub-group identicalwith CD-I-Applications: CD-Digital Audio, CD-Interactive, CD-Photo andCD-ROM and a second sub-group uses the recordable nature of theMagneto-Optical-Disc: CD erasable and the same format as CD, buterasable and recordable and CD for computer use; general purposehigh-capacity storage media for personal or home computer.

The second group of applications can be called Electronic PressApplications. Such as there are Electronic Newspapers and ElectronicMagazines, catalogues including product information with still picturesor even video sequences, educational software for correspondence course,remote downloading and updating of Point-of-sales andpoint-of-information stations and remote downloading and updating ofdatabases. It is also based on the recordable nature of theMagneto-Optical-Disc and uses the mass-distribution of multi-mediadocuments with the method described above.

The compact disc multi-media player will be used in the preferableenvironments:

CDMM and Television and Stereo Set

or

CDMM and Personal or Home Computer.

With almost the same cost as for a CD-I-only Player the CD-Multi-MediaPlayer opens the door to far more applications than what is known asCD-Interactive and becomes a Multi-Media platform for both professionaland consumer applications.

BRIEF DESCRIPTION OF THE DRAWINGS

More details of the invention will appear through the description of anon-limiting, preferred embodiment illustrated by the accompanyingdrawings.

In the drawings:

FIG. 1 illustrates the distribution concept at the broadcasting studioside.

FIG. 2 illustrates the concept at the reception side with the two kindsof storing devices CDMM-Player and digital VCR.

FIG. 3 shows a block diagram of a CDMM-Player.

FIG. 4 illustrates a configuration CD-Interactive/Recordable.

FIG. 5 illustrates a configuration Remote Recording.

FIG. 6 shows a block diagram of a digital VCR.

With the multi media system it is for example possible to transmit thecontent of 3 newspapers, 2 concerts (pure audio) and 2 filmssimultaneously. Therefore these documents stored in digital form arerequired at the broadcast studio. For example the newspapers are storedon a computer hard disc, the concerts on digital audio tape and thefilms on digital video tape.

DESCRIPTION OF THE EMBODIMENT(S)

Embodiment CDMM-Player

According to FIG. 1 on the broadcasting studio side there are providedseveral sub-channels SC1, SC2 . . . SCn with either the single or doubleCD-data-rate are fed into a multiplexer/coder MUXCC. The CD-data-rate ispreferably but not limited to 1.41 Mbit/sec. The whole number ofCD-data-rate channels is chosen in respect of the bandwidth of thetransmission channel. In the multiplexer/coder MUXCC the sub-channelsSC1, SC2 . . . SCn are time-multiplexed and control information isadded. On the whole, the commands and data of the control channelcomprise a document identification, attention that a program will startin y seconds, start of the announced program, end of the program and theencrypting. Certainly this description of the control data is notcomplete, but lists up the basic features of the control channel.Afterwards the data is undergone a forward error correction FEC toassure error-free transmission. The final step at the sending side isthe modulation by modulator MO into an analogous signal and the emissionrespectively transmission TR via the different media e.g. satellite S,cable network C or terrestrial T distribution.

At the receiving side, according to FIG. 2, the signal is fed afterreception RE into the transmission channel decoder TCD. In the TCD thesignal is demodulated, digitized and demultiplexed. Also a error checkand concealment is possible. The control information is extracted fromthe bit stream. By monitoring the control information provided with thetransmission TR the transmission channel decoder TCD causes the compactdisc multi-media player CDMM to record the distributed documentsaccording to the programming of the user. Since the compact discmulti-media player CDMM is in a stand-by mode it is necessary to wake itup. This is done by the transmission channel decoder TCD, when it hasfound a program identification x which matches with the userprogramming. The number y takes also into account the usage ofjuke-box-like multi disk players. In the control data there are alsomeans provided to realize an access permission system by encrypting thedata at the studio side and by decrypting it with a key on the receivingside.

The transmission channel decoder TCD can be housed in an external box orcan be an integrated part of the compact disc multi-media player CDMM.

The distribution can happen during the night when free televisiontransmission channels are available or in separate channels all aroundthe clock.

The compact disc multi-media player CDMM is as shown in FIG.3 a supersetof a known CD-I-Player with additional functions. This additionalfunctions are the possibility to use CD-read-only and CD-writeable suchas Magneto-Optical-Disc MOD. Further additions are the remote channelinterface RCI which offers the possibility for remote storage ofmulti-media documents on the Magneto-Optical-Disc MOD.

Optionally the compact disc multi-media player CDMM is equipped with asmart card reader SMR for access permission or prohibition to the datain the different sub-channels SC1, SC2, . . . SCn.

A further option is the computer interface for the connection to acomputer system.

As shown in FIG.4 and FIG.5 there are two groups of application in whicha compact disc multi-media player CDMM can be used.

The first group of applications relates to a first sub-group identicalwith CD-I-Applications: CD-Digital Audio, CD-Interactive, CD-Photo andCD-ROM and a second sub-group uses the recordable nature of theMagneto-Optical-Disc MOD: CD erasable and the same format as CD, buterasable and recordable and CD for computer use: general purposehigh-capacity storage media for personal or home computer.

The second group of applications can be called Electronic PressApplications. Such e.g. are Electronic Newspapers and electronicMagazines, catalogues including product information with still picturesor even video sequences, educational software for correspondence course,remote downloading and updating of downloading and updating ofdatabases. It is also based on the recordable nature of theMagneto-Optical-Disc MOD and uses the mass-distribution of multi-mediadocuments with the method described above.

The DVCR uses magnetic tape as storage media and therefore this deviceis able to store data at a data rate which corresponds to onesub-channel up to the date rate of the whole channel.

Fig. 6 shows the block diagram of a DVCR. The building blocks aresimilar to that of the CDMM. The physical storage unit is a cassettetape drive.

I claim:
 1. A method for distribution of multi-media documentscomprising the following steps:said multi-media documents in the form ofdigital signals one of said signals is demodulated, digitized,demultiplexed and control information of a digital control signal isextracted from the bit stream so that by monitoring said controlinformation signal provided with the signal, a transmission channeldecoder causes a multi-media player to record a distributed documentaccording to the programming of the user, and said signal is directlystored by a multi-media player and said stored signal is demodulated,digitized, demultiplexed and the control information of the controlsignal is extracted from the bit stream so that by monitoring saidcontrol information signal provided with the transmission, atransmission channel decoder causes a reproduction device forreproducing a distributed document according to the programming of theuser.
 2. The method according to claim 1 wherein said multi-media playeris adapted for use as a CD-I-Player and uses the recordable nature ofthe Magneto-Opitical-Disc.
 3. The method according to claim 1 whereinsaid multi-media player is adapted for use in Electronic PressApplications.
 4. The method according to claim 1 wherein saidmulti-media player is adapted for use with one of a television receiver,a radio receiver and a computer.
 5. A system for distribution ofmultimedia documents in the form of representative digital signals,comprising:one of means for demodulating a digital control signal andderiving control information from the bit stream of the control signalto enable a multi-media player to record a distributed documentaccording to the programming by the user, and means for storing saidcontrol signal by a multi-media player and demodulating said storedsignal to derive the control information from the bit stream of thecontrol signal, to enable a reproduction device to reproduce thedistributed document according to programming by the user.
 6. The systemaccording to claim 5 wherein said multi-media player is used as a CDPlayer and uses a recordable magneto-optical disc.
 7. The systemaccording to claim 5 said multi-media player is adapted for use inElectronic Press Applications.
 8. The system according to claim 5wherein said multi-media player can be coupled to one of a televisionreceiver, a radio receiver, and a computer.